On November 18, 2013, Comet Encke will pass within 0.025 AU of Mercury, followed a day later by Comet ISON at 0.24 AU (1 AU is the distance between the sun and Earth, 150 million km).
NASA’s MESSENGER spacecraft, now orbiting Mercury, will turn away from the sun’s innermost planet for a time and toward the passing comets. Astronomer Ron Vervack at the Johns Hopkins University Applied Physics Lab and a member of the science team for MESSENGER, called it:
… a unique coincidence and a golden opportunity to study two comets passing close to the sun.
Learn more from the new NASA ScienceCast below, or read more from NASA Science News
Bottom line: On November 18 and 19, Comet Encke and Comet ISON will sweep past the sun’s innermost planet, Mercury. NASA’s MESSENGER spacecraft, now in orbit around Mercury, will take this opportunity to study the comets so close to the sun.